British prime minister Theresa May warned on Wednesday there would be “difficult days ahead”, as her cabinet agreed to move forward with a draft Brexit agreement reached between UK and EU negotiators in Brussels this week.

Ms May told reporters at Downing Street on Wednesday evening that she and her ministers had had a long, detailed and impassioned debate on the draft withdrawal agreement and that she believed it was the “best that could be negotiated”.

“This is a decision which enables us to move on and finalise the deal in the days ahead,” she said. “The choices before us were difficult, particularly in relation to the Northern Ireland backstop, but the collective decision of cabinet was that the government should agree the draft withdrawal agreement and the outline political declaration.”

The draft agreement involves the UK remaining in a customs union and committing to a “level playing field” in relation to EU rules in areas like environmental and workplace protections during a backstop period after Brexit.

The backstop is an insurance policy written into the withdrawal agreement guaranteeing no harder Border on the island of Ireland. It would only be used as a last resort or the default option if the EU and UK could not reach an overarching free trade deal that would make trade so frictionless that there would be no border between the EU and the UK, including on the frontier between Northern Ireland and the Republic.

Speaking against the backdrop of boos and shouts from anti-Brexit campaigners on Whitehall, Mrs May said: “When you strip away the detail the choice before us is clear — this deal which delivers on the vote of the referendum, which brings back control of our money, laws and borders, ends free movement, protects jobs, security and our Union, or leave with no deal or no Brexit at all.”

Taoiseach Leo Varadkar said the agreement met the priorities the State had identified after the UK voted to leave the EU

Summit

The UK cabinet approval, after an hours-long meeting on Wednesday, clears the way for a special Brexit summit in Brussels — probably on November 25th — for EU leaders to approve the deal, followed by a crucial House of Commons vote on the proposal, the support for which is by no means guaranteed.

Acknowledging there would be “difficult days ahead”, Ms May said she would outline the deal to MPs on Thursday.

Michel Barnier, the chief EU negotiator, welcomed the news from London and said the draft agreement brought certainty on the consequences of Brexit.

“This agreement is decisive, a crucial step in concluding these negotiations,” he told a press conference in Brussels.

However, he warned that there was much work still to be done and that it may yet be difficult to achieve an orderly departure for the UK.

On the Northern Ireland backstop, Mr Barnier said if there was no final agreement at the end of the Brexit transition period in December 2020 they would create an “EU-UK single customs territory”.

“Northern Ireland will therefore remain in this same customs territory as the rest of the UK,” he said. “In addition, Northern Ireland will remain aligned to those rules of the single market that are essential for avoiding a hard Border.

“The UK would apply the EU’s customs code in Northern Ireland. It would allow Northern Irish businesses to bring goods in the single market without restrictions which is essential to avoid a hard Border.”

Condemnation

Ms May’s cabinet met amid a storm of condemnation for the proposed deal from Brexit-backing Tories, with prominent Leaver Peter Bone warning Mrs May that she risked losing the support of “many Conservative MPs and millions of voters across the country”.

The level of Brexiteer discontent has raised expectations of further letters of no confidence in Ms May from Tory MPs, with a total of 48 needed to trigger a vote on her position. Sources within Westminster said the delivery of letters to the chair of the backbench 1922 Committee Sir Graham Brady was “imminent”.

Jacob Rees-Mogg, head of the influential European Research Group of pro-Brexit Tories, said Mrs May’s Brexit plan was “profoundly undemocratic” and would lock the UK into the EU’s rules.

In a letter to colleagues, he said the deal would see the UK hand over £39 billion to the European Union for “little or nothing in return” and was was unacceptable to unionists because of its treatment of Northern Ireland.

In a call for revolt on the Tory benches, he said: “For these reasons I can not support the proposed agreement in Parliament and would hope that Conservative MPs would do likewise.”

Tensions were heightened by reports that senior Brussels negotiator Sabine Weyand had told ambassadors the deal will mean the UK aligns its rules with Europe, while the EU “will retain all the controls”.

‘Renege’

Earlier, at Prime Minister’s Questions, Mrs May told MPs: “We will not re-run the referendum, we will not renege on the decision of the British people.

“We will deliver Brexit and the United Kingdom is leaving the European Union on March 29th, 2019.”

Labour leader Jeremy Corbyn said the draft deal was “a failure in its own terms” and a senior spokesman said that the “likelihood” was that the party would vote against it in the Commons.

Mr Varadkar said the agreement met the priorities the State had identified after the UK voted to leave the EU - the protection of the peace process and Belfast agreement; the retention of the Common Travel Area; reaffirming Ireland’s place in the EU; and to protect trade jobs and the economy.

Taoiseach Leo Varadkar speaks at a press conference on Brexit at Government Buildings in Dublin on Wednesday night. Photograph: Niall Carson/PA Wire.

He told a press conference in Dublin on Wednesday night that the UK government’s political promise to avoid a hard border in Ireland has now been given legal weight in the Brexit withdrawal agreement.

Mr Varadkar said the previous promise to avoid a hard border - which he hailed as “bulletproof” last year - has now been strengthened.

“What I said last December is what we have to do is to turn all of the commitments that were made last December in the joint report into the legally binding text, into an international treaty, and that is what we have here today. This is even stronger than what we had back in December.”

Guy Verhofstadt, the European Parliament’s lead on Brexit, said the draft agreement endorsed by Mrs May’s government will allow Britain to leave the EU while keeping a close relationship with the bloc.

“While I hope one day the UK will return, in the meantime this agreement will make a Brexit possible, while maintaining a close relationship between the EU and UK, a protection of citizens rights and the avoidance of a hard Irish border,” he said in a statement.